The Internet, the largest worldwide network of computers.

Internets, a term used to denote lack of understanding of the Internet or technology in general; popularized after being said by U.S. President George W. Bush during a 2004 Presidential election debate with John Kerry

Internet2, a consortium of educational institutions in the United States and Europe, key in development of a high bandwidth network, Abilene Network

Plural of "internet" when used to mean "wide area networks", consisting of multiple local area networks either not using Internet Protocol or using private IP address space